Pakistan's air force closed the Peshawar-Islamabad highway on Thursday to let it practice landing jets on the road after its F-16 fighter jets soared over Islamabad and Peshawar.

HIGHLIGHTS

Jets practice landings on Islamabad-Lahore road

Tensions high after attack on Uri frontier town"

India accuses Pakistan where troops on "high alert"

Pakistan's air force closed a major highway on Thursday to let it practice landing jets on the road, in what it said was routine training not related to heightened tension with India after a deadly attack in Jammu and Kashmir's Uri.

The attack in the frontier town of Uri - the latest in a decades-long dispute over Kashmir, claimed and held in part by both India and Pakistan - has raised new fears of military conflict between the nuclear-armed neighbours.

India has accused Pakistan of being behind Sunday's attack on an army base that killed 18 soldiers in the Indian-controlled portion of Kashmir and said it had the right to respond.

Pakistan has rejected the allegation and accused India of apportioning blame before the incident had been investigated properly.

On Thursday, traffic on Pakistan's busy main highway between Islamabad, the capital, and the eastern city of Lahore was diverted to an older mountain road during the two-day air force exercise, dubbed High Mark.

"They landed on the road in this, yes. That is something they have been doing for years," Pakistan Air Force spokesman Commodore Javed Mohammad Ali said. The drill was needed "in case your runways get damaged or they are not available for you," he added.

The exercise was not ordered in response to recent tensions with India and the timing was a coincidence, he said.

"This exercise, High Mark, is not done overnight just like that," he said, describing it as "a routine training matter".

"HIGH ALERT"

Another security official, however, said the Pakistani military was on high alert in case India decided to retaliate for the Uri attack with cross-border military force.

So far, India's military response to the Uri attack has been limited to skirmishes near the Line of Control separating the countries in Kashmir.

The Indian army said on Thursday it had foiled two attempts by militants to infiltrate into Kashmir on Wednesday night.

India has long accused Pakistan of playing a role in the 27-year-long insurgency against its rule in Jammu and Kashmir.

Calls for a military response have increased since the Uri attack, particularly from some politicians within Prime Minister Narendra Modi's Bharatiya Janata Party.

Pakistan denies sending fighters into Kashmir but voices support for separatists seeking to end Indian rule there. The countries have fought two of their three wars over the Himalayan region.

India's portion of Kashmir has been under a major security lockdown during more than two months of protests triggered by the July 8 killing by Indian security forces of Burhan Wani, a young commander of the Kashmiri separatist group Hizbul Mujahideen, whose leader is based in Pakistan.

In New York, Pakistani Prime Minister Nawaz Sharif called on the U.N. General Assembly to investigate atrocities Pakistan alleges that Indian forces have committed in Kashmir.

At least 78 civilians have been killed and thousands wounded in more than two months of clashes between protesters and Indian security forces there.